1. Field of the Invention
This invention relates to a magnetic recording medium. More particularly, it relates to a magnetic recording medium composed of a high molecular non-magnetic substrate having formed thereon a subbing layer by sputtering method and a magnetic thin layer formed on the subbing layer by a vacuum deposition method.
2. Description of the Prior Art
Recently, for the purpose of improving recording density, magnetic recording media utilizing magnetic thin layer have been realized.
Conventionally, a magnetic recording tape prepared by coating a polyester film with a uniform dispersion of acicular fine particles of a ferromagnetic oxide or a magnetic metal in an organic solvent together with a binder has been generally used.
It is well known that in such a coating type magnetic recording tape, there is a limit on the recording density by the reasons that the proportion of non-magnetic components contained therein is large, the thickness of the magnetic recording layer can not be reduced over a certain limit, etc.
On the other hand, a method of forming a thin layer of a magnetic metal on a film support by a physical vapor method, such as vacuum vapor deposition, ion plating, sputtering, etc., can be expected to improve the recording density of the magnetic recording medium since the magnetic recording layer can be greatly thinned and almost all the magnetic recording layer is a magnetic component.
However, although the aforesaid method has been studied to commercialize some of these magnetic recording tapes and has been noticed as an effective method to produce thin layer magnetic recording media, in spite of the foregoing facts, the aforesaid method has not been widely used at present because there is a fault about the adhesive property and peeling resistance between the polyester film and the thin magnetic recording layer and hence in the case of using the method for producing a magnetic recording tape, there are problems about the wear resistance and the durability of the magnetic recording tapes.